You can use Infinispan (the successor of JBossCache) in two modes
here Infinispan is a separate instance
the infinispan is within the same JVM as JBoss
both modes have different benefit.
You should start with the docs and examples here Infinispan Homepage - Infinispan
Regarding performance, the cache can boost your application performance, but it depends on your use-case.
As a rule of thumb, as slower your database or backend is as more a cache will help
I would love to work on Infinispan. I'm running my AS on Windows OS. Do we have anything documented how to configure infinispan in Jboss7.1AS running in windows?